1. Field of the Invention
The disclosure relates to a backlight unit and a liquid crystal display (LCD) having the same. More particularly, the disclosure relates to a backlight unit capable of improving productivity and reliability by improving the assembling efficiency thereof, and an LCD having the same.
2. Description of the Related Art
An LCD displays images using electrical and optical properties of liquid crystal. Since the LCD has advantages of slimness, lightweight, low power consumption and low driving voltage as compared with other display apparatuses, the LCD has been extensively employed in various industrial fields.
The LCD includes a liquid crystal display panel, in which liquid crystal is interposed between two transparent substrates and voltage is applied to the liquid crystal to change a direction of liquid crystal molecules to optically display images, and a backlight assembly for providing light to the liquid crystal display panel.
A CCFL (Cold Cathode Fluorescent Lamp), an EEFL (External Electrode Fluorescent Lamp), and an FFL (Flat Fluorescent Lamp) are used as light sources of the backlight assembly. However, the CCFL represents limitations in terms of high definition, light weight, slim structure and compact size, so an LED (Light Emitting Diode) has been recently used as the light source of the backlight assembly because the LED represents improved performance such as high brightness, long life span and high color purity. In addition, as restriction on dumping of dangerous substances such as mercury has been reinforced, the CCFL is less used, and the LED, which is an environmental friendly device, is widely used instead of the CCFL.
The backlight assembly having such an LED as the light source is classified into a direct-type backlight assembly and an edge-type backlight assembly according to the arrangement of the LED and the type of the light guide plate. The direct-type backlight assembly having the LED has a structure in which the LED is disposed in front of the backlight assembly, so the direct-type backlight assembly has a difficulty in achieving slimness and requires a large number of LEDs, increasing the manufacturing cost.
In contrast, the edge-type backlight assembly has a structure in which the LED is mounted at both sides of the backlight assembly and light is introduced into the front surface of the backlight assembly through a light guide plate, so the edge-type backlight assembly may have a thickness smaller than that of the direct-type backlight assembly, thereby realizing the slimness structure.
A backlight unit provided with the LED includes a box-shape bottom chassis having an open upper surface to sequentially receive a reflection plate, the light guide plate and optical sheets therein. In addition, a plurality of LEDs mounted on the printed circuit board are provided adjacent to a side of the light guide plate in the backlight unit.
Since the PCB is fixed to an inner wall surface of one side of the bottom chassis using a screw by a worker, a defect may occur during the assembling process. Further, a screw hole and a circuit pattern have to be formed in the PCB although the PCB has a small area.